Slam dunk dilemma!

Zac dreams of being a tall basketball player like his brother, Cam, who can easily perform slam dunks. Zac can't magically grow any taller but he can buy the Ultra Bounce trainers he's seen at the charity shop. They fit perfectly and soon Zac finds himself jumping higher than ever and scoring so many goals... Are the shoes really magical? And if so, does that mean he's cheating? Zac's in a total dilemma!